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-   -   weathertron Mecury Thermostat (http://www.diychatroom.com/f17/weathertron-mecury-thermostat-94671/)

VickiL 02-06-2011 01:57 AM

weathertron Mecury Thermostat
 
My husband took off our old Weaathertron Mecury THermstat and we now can't rewire it to our heatpump. Can any one help. the terminals aare g y x2 b t r o f w the colors of wire are white, green, red, blue, brown, yellow,black and one other I forget the color. Which color goes to which terminal PLEASE:help::help:

beenthere 02-06-2011 08:12 AM

Can't say without knowing where they connect at the other end. Low voltage wiring doesn't have an actual color code that is used by all techs.

Jackofall1 02-06-2011 09:13 AM

The only way to tell is to go the other end of the wire, at the furnace, write down the color a terminal number/letter/or description/or picture and then if it isn't obvious post description or picture back here.

Good Luck

Mark

diyorpay 02-06-2011 09:36 AM

This comes from web and has many cautions, particularly that the original installer may not have followed the "normal" color coding. But it may be helpful too. Draw out your plan on paper before wiring.

Thermostat Terminal Designation
Color of Wire and Termination
R – The R terminal is the power for the thermostat. This comes from the transformer usually located in the air handler for split systems but you may find the transformer in the condensing unit. For this reason, it is a good idea to kill the power at the condenser and the air handler before changing or working on the wiring at the thermostat. If you have a package unit then the transformer is in the package unit.
Red for the R terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didn’t use conventional color coding.
RC – The RC terminal is designated for the power for cooling. Some HVAC systems use two transformers. A transformer for cooling and a transformer for heating. In this case the power from the transformer in the air conditioning system would go to the thermostat terminal. It should be noted that a jumper can be installed between RC and RH for a heating and cooling system equipped with a single transformer.
Red for RC terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didn’t use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
RH – The RH terminal is designated for the power for heating. See RC above for an explanation. It should be noted that a jumper can be installed between RC and RH for a heating and cooling system equipped with a single transformer.
Red for RH terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didn’t use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
Y – This is the terminal for cooling or air conditioning and goes to the compressor relay. Typically a thermostat wire pull is made to the air handler on split systems and then this wire is spliced for the separate wire pull which is made to the condenser. Some manufacturers put a terminal board strip near the control board in the air handler so a splice is not needed.
Yellow for Y Terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didn’t use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
Y2 – This is the thermostat terminal for cooling second stage if your system is so equipped. Many systems only have a single compressor but if you have two compressors which should only operate off of one thermostat then you need the Y2 thermostat terminal for second stage cooling.
*The most common color I’ve seen used for this terminal and wire designation is light blue but this varies and is completely up to the installer what color to use. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
W – This is the thermostat terminal for heating. This wire should go directly to the heating source whether it be a gas or oil furnace, electric furnace, or boiler,
White for W Terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didn’t use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
W2 – This is the thermostat terminal used for second stage heat. There are gas furnaces with low fire and high fire and some depend on control from a two-stage heating thermostat with a W2 terminal. Heat Pumps use staging for auxiliary heat and need a W2 terminal.
*The most common color I’ve seen used for this terminal and wire designation is brown but this varies and is completely up to the installer what color to use.
G – This is the thermostat terminal used for the fan relay to energize the indoor blower fan. On a split system the blower fan is in the air handler while with a package unit the blower fan is in the outdoor package unit.
Green for G Terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didn’t use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
C – This is the thermostat terminal which originates from the transformer and is necessary to complete the 24 volts power circuit in the thermostat but only if the thermostat consumes electricity for power. Many digital thermostats require 24 volts for power so the common wire is necessary.

C stands for common and there is no universal color used for this terminal although black is the most common color I’ve seen.


**Heatpumps are different. X terminals refer to heat strips and emergency power and are not included above. Do a search of this site for heat pump wiring.

hvaclover 02-06-2011 05:32 PM

Quote:

Originally Posted by diyorpay (Post 585655)
This comes from web and has many cautions, particularly that the original installer may not have followed the "normal" color coding. But it may be helpful too. Draw out your plan on paper before wiring.

Thermostat Terminal Designation
Color of Wire and Termination
R Ė The R terminal is the power for the thermostat. This comes from the transformer usually located in the air handler for split systems but you may find the transformer in the condensing unit. For this reason, it is a good idea to kill the power at the condenser and the air handler before changing or working on the wiring at the thermostat. If you have a package unit then the transformer is in the package unit.
Red for the R terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didnít use conventional color coding.
RC Ė The RC terminal is designated for the power for cooling. Some HVAC systems use two transformers. A transformer for cooling and a transformer for heating. In this case the power from the transformer in the air conditioning system would go to the thermostat terminal. It should be noted that a jumper can be installed between RC and RH for a heating and cooling system equipped with a single transformer.
Red for RC terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didnít use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
RH Ė The RH terminal is designated for the power for heating. See RC above for an explanation. It should be noted that a jumper can be installed between RC and RH for a heating and cooling system equipped with a single transformer.
Red for RH terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didnít use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
Y Ė This is the terminal for cooling or air conditioning and goes to the compressor relay. Typically a thermostat wire pull is made to the air handler on split systems and then this wire is spliced for the separate wire pull which is made to the condenser. Some manufacturers put a terminal board strip near the control board in the air handler so a splice is not needed.
Yellow for Y Terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didnít use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
Y2 Ė This is the thermostat terminal for cooling second stage if your system is so equipped. Many systems only have a single compressor but if you have two compressors which should only operate off of one thermostat then you need the Y2 thermostat terminal for second stage cooling.
*The most common color Iíve seen used for this terminal and wire designation is light blue but this varies and is completely up to the installer what color to use. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
W Ė This is the thermostat terminal for heating. This wire should go directly to the heating source whether it be a gas or oil furnace, electric furnace, or boiler,
White for W Terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didnít use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
W2 Ė This is the thermostat terminal used for second stage heat. There are gas furnaces with low fire and high fire and some depend on control from a two-stage heating thermostat with a W2 terminal. Heat Pumps use staging for auxiliary heat and need a W2 terminal.
*The most common color Iíve seen used for this terminal and wire designation is brown but this varies and is completely up to the installer what color to use.
G Ė This is the thermostat terminal used for the fan relay to energize the indoor blower fan. On a split system the blower fan is in the air handler while with a package unit the blower fan is in the outdoor package unit.
Green for G Terminal. *Although be aware that this may have changed especially if the person who wired the thermostat didnít use conventional color coding. Most installers use the color coding as noted but be aware that some do not use the thermostat color coding.
C Ė This is the thermostat terminal which originates from the transformer and is necessary to complete the 24 volts power circuit in the thermostat but only if the thermostat consumes electricity for power. Many digital thermostats require 24 volts for power so the common wire is necessary.

C stands for common and there is no universal color used for this terminal although black is the most common color Iíve seen.


**Heatpumps are different. X terminals refer to heat strips and emergency power and are not included above. Do a search of this site for heat pump wiring.

The OP was asking about terminal location by color.

I might get jumped for this but what i would is got to where the wires connect at the heat pump and see where your left over wire connects.


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